Television service providers periodically send television system messages to electronic devices configured for use with their television systems. The television system messages may contain application data such as an electronic program guide (EPG) and system information such as channel mapping parameters (e.g., channel frequency, modulation mode and virtual channel number reference) for accessing television services.
Device circuitry within the electronic devices processes the system messages. Television service providers typically require that the device circuitry is continuously “powered up,” even if the electronic device is in a low power mode such as a standby mode. If the device circuitry is not powered up, system message may be missed and it may take several hours for redistribution of the system messages, e.g., due to a “carousel” format of the National Authorization Service (NAS) commonly used to distribute system messages. Prior to receiving the system messages, the device circuitry may incorrectly tune channels or exhibit undesirable operating effects.
The television system messages may occur infrequently and generally have a duration of a few seconds to a few minutes. Thus, when the electronic device is in the low power mode, the device circuitry remains fully powered even though it is rarely used. Since there is an ever present desire to reduce the amount of energy consumed by electronic devices, there is a need for methods and apparatus for processing system messages without requiring that the device circuitry is continuously powered up. The present invention fulfills this need among others.